Device for converting a physical pattern into
an electric signal as a function of time
utilizing an analog shift register

ABSTRACT

A DEVICE FOR CONVERTING ENERGY PATTERS IN THE FORM OF LIGHT, PRESSURE, HEAT OR MANGETIC IMAGES INTO AN ELECTRICAL SIGNAL AS A FUNCTION OF TIME WETHER THE NECESSITY FOR A SCANNING BEAM OR A CROSSED BAR READOUT SYSTEM IS ELIMINATED BY CASCADING ELEMENTS WHICH FUNCTION AS BOTH STORAGE AND ENERGY SENSITIVE DEVICES AND BY PROVIDING CIRCUITRY FOR SHIFTING (THE) CHARGES (OF THE ENERGY SENSITIVE STORAGE) STORED IN THE ELEMENTS IN A SINGLE DIRECTION ALONG THE CASCADED ARRAY.

March 26, 1974 TEER ETAL Re. 27,951

DEVICE FOR CONVERTING A PHYSICAL PATTERN INTO AN ELECTRIC swmu, AS AFUNCTION OF mm UTILIZING AN ANALOG SHIFT REGISTER Original Filed April17, 1969 4 Sheets-Sheet 1 March 26, 1974 E ETAL DEVICE FOR CONVERTING APHYSICAL PATTERN INTO AN ELECTRIC SIGNAL AS A FUNCTION OF TIME UTILIZINGAN ANALOG SHIFT REGISTER Original Filed April 17, 1969 4 Sheets-Sheet 2n u H u n u u 1.| i d I n a J .m n u M It I I I I II n n n Fl 2 2 2 w+|||3 MW 1 1. I

o i l fig.2

March 26, 1974 K. TEER FI'AL Re. 27,951

DEVICE FOR CQNVERTING A PHYSICAL PATTERN INTO AN ELECTRIC SIGNAL AS AFUNCIIGN OF TIME UTILIZING AN ANALOG SHIFT REGISTER Original Filed April17, 1969 4 Sheets-Sheet 5 L 1 2 T H T j" I m 1% L J': ----.,.x

m' m? 412 IT In H1 i P, 0

March 26, 1974 7559 ETAL DEVICE FOR CONVERTING A PHYSICAL PATTERN INTOAN ELECTRIC SIGNAL AS A FUNCIION OF TIME UTILIZING AN ANALOG SHIFTREGISTER 4 Sheets-Sheet 4 Original Filed April fig.4a

IIJWI fig.4b

United States Patent 68 Int. Cl. G06g 7/12; H011 11/14 US. Cl. 307-22912 Claims Matter enclosed in heavy brackets appears in the originalpatent but forms no part of this reissue specification; matter printedin italics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE A device for converting energy patterns inthe form of light, pressure, heat or magnetic images into an electricalsignal as a function of time where the necessity for a scanning beam ora crossed bar readout system is eliminated by cascading elements whichfunction as both storage and energy sensitive devices and by providingcircuitry for shifting [the] charges [of the energy sensitive storage]stored in the elements in a single direction along the cascaded array.

The invention relates to a device for converting an energy pattern intoan electric signal as a function of time, which device comprises atleast one row of pickup elements. In the pickup elements, which comprisea semiconductor circuit element, the information of the energy patternis converted into an electric voltage corresponding thereto in valueacross a capacitance in a pickup element.

Such a device, for example, for observing a scene optically or in theinfrared range is known from the article Charge Storage Lights the Wayfor Solid-State Image Sensors by G. P. Weckler in Electronics," May 1,1967, pp. 75-78.

In the said articles pickup elements are described inter alia whichcontain semiconductor metal oxide (MOS) transistors. A PN-junction ofthe MOS transistors of the P-channel type brought in the cutoffcondition serves as a capacitance. The radiation from the scene to beobserved is incident on said capacitance. Dependent upon the intensityof the radiation more or fewer holes and electrons will be created inthe boundary layer between the semiconductor P- and N-layers whichdischarge the capacitance by recombination with the charge provided onthe capacitance. By subsequently charging the capacitance again by meansof a pulsatory voltage and determining the charge required for thatpurpose, an indication regarding the intensity of the incident radiationis obtained for a pickup element in the form of an electric signal.

Pickup elements forming a pickup array are also described in thearticle, in which the capacitances collecting the radiation areconstituted by phototransistors, the pulsatory charging voltage beingapplied through MOS transistors serving as switches. It is proposed touse a system of crossed bars to obtain the electric signal representingthe physical information from the pickup elements. The pickup elementsare provided between the intersections of two pairs of intersectingparallel conductors. The pickup elements are thus connected in rows andcolumns by means of the conductors. By applying a switching signal toone of the row conductors and one Re. 27,951 Reissued Mar. 26, 1974 ofthe column conductors, the electric signal representing the radiation isobtained, through the MOS transistor operating as a switch, from thepickup element arranged between the relative conductors.

The reading out of the said pickup array by means of a system of crossedbars, presents many problems and disadvantages. The intersectingconductors of the system of crossed bars are located close to eachother. Therefore, comparatively large stray capacitances are presentbetween the conductors. Since for reading out the pickup elements ahigh-frequency switching signal is required said stray capacitances givea disturbing crosstalk effect.

Since the requirement holds that only one pickup element of a row or ofa column should provide its information, the result is that between therelative pickup element and the conductor, a small resistance must bepresent and between the other pickup elements and the conductor a largeresistance must be present. For that purpose it is stated in theabovementioned article that in each phototransistor operating as acapacitance, a MOS transistor must be provided which serves as a switch.It also holds that a conductor must be very low-ohmic in order that theswitching signal be attenuated by the conductor as little as possible.The attenuation and, for example, the voltage drop across the conductorresulting therefrom, may in fact have for its result that a pickupelement other than the relative pickup element also providesinformation. The requirements of the readily conducting material for theconductor for which, for example, aluminum is suitable, presentsdifficulties in integration methods for the pickup elements constructedwith semiconductor material as regards the provision and the requiredconnections.

In addition at least two shift registers are required for supplying theswitching signal to the rows and to the columns.

It is the object of the invention to provide a device which does notexhibit the abovementioned drawbacks associated with a system of crossedbars, in which also the influence of stray capacitances occurring isused to advantage. The device according to the invention pro vides anentirely new method of reading out the pickup elements and for thatpurpose it is characterized in that the capacitance in a pickup elementis present between an output electrode and a control electrode of thesaid semiconductor circuit element. The control electrode is connected,through a voltage source which can produce a voltage having a value as afunction of time cutting off the semiconductor circuit element, to acontrol electrode of another semiconductor circuit element between theoutput electrode and control electrode of which another capacitance ispresent. The output electrode of one semiconductor circuit element iscoupled to the input electrode of the other semiconductor circuitelement [,1 A transport of charge which depends upon the information ofthe radiation pattern [occurring] occurs in said coupling between onecapacitance and the other capacitance as a result of bringing the othersemiconductor circuit element in the conductive condition by means ofthe said voltage source.

In order that the invention may be readily carried into effect, a fewexamples thereof will now be described in greater detail with referenceto the accompanying drawings.

FIG. 1 shows a device according to the invention in which the pickupelements are provided with semiconductor circuit elements constructed asMOS transistors.

FIG. 2 serves to explain the operation of the device shown in FIG. 1 andshows diagrammatically a few diagrams as a function of time.

FIG. 3 shows a device according to the invention provided with severalrows of pickup elements.

FIGS. 4a and 4b show an example of an embodiment of the pickup elementsin lC-form of a device according to the invention.

Referring now to FIG. 1, of a device according to the inventionconstructed with a number of pickup elements 1 to n which arecollectively denoted by pickup elements B to B the first three pickupelements B B and B are shown in detail. Since the pickup elements B to Bare constructed in the same manner, a detailed description is given ofthe pickup element B only. The pickup element B comprises two[semiconductor] semiconductor circuit elements, denoted as transistors Tand T which are further constructed as semiconductive metal oxide (MOS)transistors of the N-channel type. An input or source electrode denotedby S and an arrow indicating the direction of current of MOS transistorT, is connected to an output or drain electrode of MOS transistor Tdenoted by D, while of MOS transistors T and T, a {mass or] common biaselectrode 8 arranged on the substrate of each transistor is connected toa terminal having a negative potential V,,. The terminal which is at thepotential V,, forms part, in a manner not shown, of a direct voltagesource V another terminal of which is connected to ground. The same willapply to further direct voltage sources to be mentioned in thedescription. A control or gate electrode G of MOS transistors T and Trespectively, is coupled to the drain electrode D through a capacitancedenoted as capacitors C and C, respectively.

The pickup elements B to B are connected together by connecting of eachpickup element, except for the last pickup element B the sourceelectrode S of MOS transistor T, to the drain electrode D of the MOStransistor T in the succeeding pickup element and by interconnecting thegate electrodes G of the MOS transistors T and T respectively. Thesource electrode S of the MOS transistor T, in the pickup element B (notshown) may be connected both to a terminal having positive potential andmay not be connected further, that is to say, it may be kept floating.The drain electrode D of the MOS transistor T in the pickup element B isconnected to the source electrode S of a MOS transistor T the biaselectrode B of which is connected to the terminal having a negativepotential --V and the gate electrode G is connected to that of MOStransistors T In the pickup elements B B and B13, the potentials at thedrain electrodes D of the MOS transistors T and T respectively, aredenoted V11, V and V and V V and V respectively.

The interconnected gate electrodes G of MOS transistors T MOStransistors T and MOS transistors T respectively, are connected toground, through voltage source P and P respectively. Voltage sources Pand P produce the clock voltages U and U, as a function of time shown inFIG. 1, which voltages vary between the ground potential denoted by zeroand a potential 'value +13. The voltage U; produced by the voltagesource P, lags half a period with respect to voltage U which is suppliedby the voltage source P The drain electrode D of MOS transistor T isconnected to ground through a capacitor C Parallel to the capacitor C isconnected a voltage source I, which supplies a clock voltage U as shownthrough a diode D connected with its cathode to capacitor C The voltageU having a square-wave form as a function of time varies between thepotential value +E and a reference value +2E. The terminal of thecapacitor C having a potential V is connected to the gate electrode G ofa MOS transistor T of the N-channel type, the bias electrode B and thedrain electrode D, respectively, being connected to a terminal having apotential -V,, and 4-, respectively. The source electrode S of MOStransistor T is connected to ground through a resistor R and the voltageproduced across the resistor R dependent upon the value of potential Vappears at an output terminal Z of the device.

Instead of MOS transistors, germanium transistors or silicon transistorsmay alternatively be used in the device. The said input or sourceelectrode S and output or drain electrode D correspond to an emitter andcollector electrode respectively. The said gate electrode [6] Gcorresponds to a base electrode, which two electrodes may collectivelybe referred to as control electrodes.

As is known, the construction of the said transistors [T T T T and T asMOS transistors, as compared with normal germanium or silicontransistors for the same drive, presents the advantage of a very muchsmaller value of the current through the gate electrode G than throughthe base electrodes of the normal transistors. Of course, normaltransistors in the known Darlington arrangement could also be used toobtain the same effect, or the loss of charge corresponding to the saidbase current could be eliminated by providing charge amplifiers betweena few pickup elements. Alternatively, transistors using a field-effect(so-called FETs) are to be considered.

In the embodiment shown the physical pattern which is to be convertedinto an electric signal influences the voltage across the capacitors [C1and C2] C and C, and hence the values of the potentials V11, V V12, Vand so on, by a physical interaction which is denoted diagrammaticallyby [arrows in] dot-and-dash lines. As already stated in theabove-mentioned Weckler article, the interaction may be photoelectric.The capacitors C and C each denote the essentially parallel capacitanceof the PN-junction of the substrate-drain diode in the MOS transistors Tand T and that present between the gate electrodes G and the drainelectrodes D. In the capacitors C and C shown the stray capacitances areincluded in the MOS transistors T and T and these are thus used toadvantage.

It is also possible to construct capacitors C and C, as separatecomponents having a leak resistance, the value of which depends upon thenumber of incident photons, for example, the dielectric of a parallelarranged photoresistor. Alternatively a pattern characterized by apressure distribution or a geometry of unevenesses could act upon thedielectric constructed with piezc oxides, or on, for example, pressuresensitive resistors connected parallel to the capacitor C and C The sameapplies to a. magnetization pattern, the magnetic field distribution ofwhich influences the value of a resistor which is sensitive to magneticfields. For that purpose the resistor may consist, for example, of anInSb-mass, in which NiSb-needles occur. The magnetic field influencesthe position of the NiSb-needles readily conducting electric current inthe InSb-mass poorly conducting electric current.

The operation of the device according to the invention shown in FIG. 1will now be explained with reference to the diagrams shown in FIG. 2.The diagrams shown in FIG. 2 as a function of time give the voltages U Uand U supplied by voltage sources P P and P and the potentials V0, V11,V V13, V12, V1 and V occur at the places already shown in FIG. 1. Toexplain the operation of the device shown in FIG. 1 it is sufiicient toconsider a device having only three pickup elements B 1, B and B It isassumed that the source electrode S of MOS transistor T in the pickupelement B is kept floating. To obtain a closely reasoned explanation ofthe cyclic operation of the device a given condition is started from. Itwill appear that after the period to be explained, the assumed givencondition is again reached automatically. The period of the square wavevoltage U is shown in FIG. 2 with a few time intervals t to t t to t,;-t to 1:13.

In FIG. 2 an instant t -At is shown shortly after which the potentialsshown V V V V V and V all appear to have the value +E, which thepotential V is equal to +213. Starting from the instant t at in which atime interval denoted by M for television will be found to lie in theorder of a few tens of milliseconds,

the following occurs in the time interval M the value of the voltages U;and U, supplied during the time interval At to the gate electrodes G ofMOS transistors T T and T by voltage sources P and P is equal to groundpotential, so that said transistors are cutoff during the time intervalAt due to the higher potential at the source electrodes S. In the timeinterval At the value of the voltage U, supplied by the voltage source Pvaries between the potentials +2E and +13. Since the potential V has thevalue +2E and keeps it during the time interval At when leakage lossesare negligible, the diode D will not conduct. In order to show that, forexample, for television, the time interval M is relatively long withrespect to the recurrence period of the voltage U the voltage U duringthe time axis denoted by a broken line, shortened relative to that whichis shown by a solid line, is shown again with an apparently more rapidlyvarying square-wave voltage. During the comparatively long time intervalAt the energy pattern to be converted influences the voltage across thecapacitors C and C and causes it to decrease dependent upon the value ofthe information. Assuming the information in the form of photons torepresent a scene to be picked up, the light from the scene varying inbrightness from white peak via gray to black, it may be assumed that,for example, the bright white light impinges upon capacitor C of pickupelement B and no light impinges upon the capacitor C of the pickupelement B while the intermediate grey values are evently distributedbetween the other capacitors C, and C The result is that during the timeinterval at the potentials V V V V and V decrease, while the potential[V V for negligible dark current, remains constant. The potential dropduring the time interval At is shown linearly in FIG. 2, which, however,is not required. A nonlinear, for example, exponential drop is alsoreadily possible. As will become apparent in the course of thedescription, the minimum occurring potential value for the maximum valueof the brightness of the light should not be smaller than /2E. Thisvalue is reached for white peak, by the potential V at the end of thetime interval At that is to say at the instant t It is found that thepotentials V to V at the end of the time interval At have values L]which, dependent upon the brightness of the ]light, vary from /fiE forwhite peak to +13 for blac At the instant t the value of the voltage Usupplied by the voltage source P steps from ground potential 0 to +E.The result is that this potential step is impressed upon the gateelectrodes, G of the MOS transistors T and the terminals of capacitors Cconnected thereto. As a result of this the potential step having thevalue E will simultaneously occur, through the capacitors C in thepotentials V11, V and V13, so that these reach values at the instant twhich lie between +116 and approximately [+3E] +2E. The potential stepfrom 0 to +E. on the gate electrode G of M08 transistor T sets it in theconductive condition if the potential V at [the] its source electrode Sis lower than +E, which potential V is in turn determined by the chargecondition of C and applied potential U As a result of this thecapacitors C and C3 in the pickup elements B and B are connectedtogether until, apart from threshold voltages. the value of thepotential at the source electrode S has become equal to that at the gateelectrode G of the MOS transistor T The charge required therefor cannotbe applied through the gate electrode G but must be supplied from thecapacitor C through the drain electrode D and the source electrode S tothe capacitor 0,. Starting from substantially the same values of thecapacitors C and C, it is found that, as shown in FIG. 2 in the timeinterval t to t the respective potentials V and V will have to decreaseas much.

as the respective potentials v and V will increase.

Since no light has impinged upon the capacitor C in pickup elements Bthe [change] charge of the capacitor C, has remained constant. Thepotential step from 0 to +13 at the gate electrode G of MOS transistor Tin pickup element B13, Will therefore not cause the same to becomeconductive.

The result of the potential step in the voltage U at the instant t isthat in a pickup element the loss of charge in the capacitors C due tothe charging to the potential +E, has been transferred to the capacitorC through the source electrode S and the drain electrode D of theconductive MOS transistor T The potentials V V and V thus obtain a givenvalue relative to the value +2E which difference value corresponds tothe brightness of the light which is incident on the pickup elements BB12 and B13- At the instant t the value of the voltages U and Urespectively, supplied by the voltage sources P and P respectively,steps back from the value +E, and +2E, respectively, to ground potentialand potential value +E, respectively. Simultaneously the voltage U,supplied by the voltage source P steps from ground potential up to thevalue +E. The potential step in the voltages U and U respectively, showa potential step E downwards and upwards, respectively. In the pickupelements B11, B and B the so far cutofl MOS transistors T, will becomeconductive instead of the MOS transistors T as it also holds for MOStransistor T As a result of this, the terminal of capacitor C which hasa potential V equal to +2E, is connected through MOS transistor T to theterminal of capacitor C in pickup element B which has a potential VSince potential V is lower than +E, which value is impressed upon thegate electrode G of MOS transistor T by the voltage source P with'voltage U the potential V will increase to the value +E. As alreadydescribed above, the charge required for that purpose will have to besupplied by capacitor C For a value of capacitor C equal to that ofcapacitor C in pickup elements B11, the increase of potential V will beequal to the drop of potential V The same phenomenon presents itselfbetween the pickup elements 11, B12 and B the loss of charge in thecapacitors C in the pickup elements B and B respectively, beingtransmitted to the capacitor C in pickup elements B and B This isexpressed in FIG. 2 when the potentials V V and V respectively, arecompared with the potentials V V and V respectively, during the statedtime interval t to t During this time interval t to t the diode Dremains cut oil since the value of the voltage U is equal to +E.

The potential V decreased from +2E to approximately "+E, causes throughthe [transistor] resistor R a smaller current to flow through the MOStransistor T so that relative to ground a voltage occurs at the outputterminal Z of the device which is equal to potential V The voltage dropoccurring at the output terminal Z, thus represents the brightness ofthe light which impinges upon the pickup element B At the instant t apotential step occurs in the voltages U U and U after which thesevoltages obtain the same value as shortly after the instant t The resultis the same operation of the device as already described at the instantt A dilference is, however, that in the time interval t to t thepotential V. will increase to the value +2E, since this value isimpressed by the voltage source P, through the conductive diode D;,.

For illustration FIG. 2 shows a part of the potential variations whichcorrespond to the brightness of the light incident upon the pickupelement B as a shaded area. It can simply be seen that during the timeinterval t to t the information given by the value of potential V,,relative to +'E is transmitted to the potential V and is superimposedthereon relative to the value +2E. During the time interval t to t thetotal information which is suppiied to the pickup element B during thetime interval M is transferred to the capacitor C3 in the pickup elemeat8;; as a result of which the potential V; varies relative to the value+2E. During the period t to [t the information of the pickup element Bis transferred in the pickup element B from the capacitor C having apotential V to capacitor C having a potential V The result is that inthe time interval t to t the information given by the pickup element Bis transferred to the capacitor C and hence to the Output terminal Z.The information of the pickup element B becomes available at the outputterminal Z for further processing in the time interval t to t It hasbeen found that for reading out a device comprising three pickupelements it is necessary and sufficient that the voltages U and Usupplied by the voltage sources P and P show three square-wave pulsesduring the time interval t to t From this it appears that shortly afterthe instant t the value of the potentials V V V V and V V is equal to +Ewhile that of potential V is equal to +2E. As already described above itis found that after reading out the device, the condition isautomatically reached from which was started for the explanation. Theresult is that the instant t for a cyclic operation of the devicecorresponds to the instant t At For a device comprising n-pickupelements 8 B [b B to B in which a time interval M in which the light ofthe scene to be picked up influences the potemiflls 11 11 12. 12 13 iaim m' must be comparatively large relative to the time interval t to tThis requirement does not hold for a device in which the information ofthe physical pattern is written instantaneously without integration intime. An example thereof may be a device in which a patterncharacterized by a pressure distribution in an instantaneous mannerinfluences the potential picture of the dielectric constructed with apiezo oxide of capacitors C and C It is obvious from the variation ofthe potentials V and V that the potential drop under the influence ofthe light from the scene for white peak cannot be more than /2E. If infact the light impinges upon both capacitors C and C in the pickupelement B with maximum brightness that is to say white peak, thepotential V will decrease from +l /2E to +E in the time interval t to tThe result is that shortly before the instant t the potential V at thedrain electrode D, the potential V at the source electrode 8, and thepotential at the gate electrode G of MOS transistor T in the pickup element B all have the value +E. If, however, the potentials V and V shouldexperience a larger drop than AB and reach, for example, the value +%E,the potential V will decrease from +lVsE to +E in the time interval t tot Due to this the potential V can only increase by VsE to the value+/sE. Since for a correct operation of the device it is required thatthe potential V at the source electrode S increases to the referencevalue +E, the limit already set results.

The stated limit of /2E for the potential droo does not hold for thecase in which in each picku: element the voltage across the capacitor Cor C is not influenced by the physical information but is kept constantat the reference value +E, so that the reference value is alwaysavailable in a pickup element. As a result of this the other capacitorin the pickup element may experience a voltage drop by the value B, somay be substantially [be] discharged without interfering with thecorrect operation of the device. This may be realized, for example, byscreening the dielectric of a capacitor C or C in each pickup elementfrom the physical information or making it insensitive thereto.

When the device is actuated the charging of the capacitors C and C inthe pickup elements B B B and B occurs in a simple manner by means ofthe voltage sources P P and P already described with reference toFIG. 1. The squarewave voltage U supplied by the voltage source Pcharges the capacitor C [at] to the value +2E via diode D so that thepotential V obtains the value +2E. The voltage U; supplied by thevoltage source P, then makes the MOS transistor [t T conductive at thevalue +E so that in the manner already described the potentials V and Vobtain the value +5. The voltage U, supplied by the voltage source P;then renders the MOS transistor [t T, conductive at the value +E so that[as a result of the charge distribution between two capacitors,] thepotentials V and V obtain the values 0 and E respectively [value +5613].Simultaneously, the capacitor C is charged again so that the potential Vagain has the value +2E. In a following period it is achieved that thepotentials V and V reach the values 0 and E respectively [value /SE].After n periods the potentials V and V are equal to 0 and B respectively[2(l2n)E, which value then rapidly increases]. Due [due] to the furthercharging of the preceding capacitors C and C3 [until] after some time avoltage having substantially a value +E is available across all thecapacitors C and C2 present in the pickup elements B B12, B to B Thisinstant corresponds to the instant t -At in FIG. 2. Of course, thecharging can be accelerated by increasing the frequency of the voltagesU1, U2 and U3.

For analyzing optical, magnetic, or other physically given phenomenawhich manifest themselves in a onedimensional pattern it is possible, asshown in FIG. 1, to use a single row of pickup elements for convertingthe physical pattern into an electric signal as a function of time. Ifitshould be desirable to convert the information in a two-dimensionalmanner, the device shown in FIG. 3 provides a solution.

FIG. 3 shows a device according to the invention which is provided withm rows having n pickup elements. Since a row of pickup elements B11, B Bto [B B was already described with reference to FIG. 1, and since inFIG. 3 the rows are constructed in an equivalent manner, the componentsof the pickup elements are not shown in detail. Further componentsalready shown in FIG. I are denoted by the same reference numerals inFIG. 3 at least substantially. The MOS transistor T associated with therow in FIG. 1, which for reading a row of pickup elements connects thesame to the capacitor C is constructed m-fold in FIG. 3 and is denotedfor the TOWS l, 2, 3, m, 1,1 T01, T02, T03 T Instead of the sourceelectrode S of the MOS transistor T in the last pickup element B whichin the explana tion of FIG. 1 was assumed to be floating, thecorresponding source electrodes S of the MOS transistors T in the lastpickup elements B Ban, B to B in FIG. 3 are connected together andconnected to a terminal having a potential +V All this is not essentialfor the invention.

The device shown in FIG. 3, may serve, for example, as a televisioncamera, in which the light from the scene to be picked up is incident onthe pickup elements B to B In order to obtain the image signal producedby the camera at the output terminal Z, the voltage U is shown at aninput terminal X of the camera which voltage is produced by a voltagesource P not shown. In order to obtain the voltages U and U: a combinedvoltage source (P P is shown which may comprise, for example, asymmetical bistable trigger circuit which is pulsed by the voltage U Thevoltage U, is also applied to an rt-divider (denoted by n). The outputvoltage of the n-divider is applied to an m-divider (denoted by m) andto each of the shift register stages K K K to K constituting a shiftregister. The voltage supplied by the m-divider is applied to the firstshift register stage K The outputs of the shift register stages K K K toK are connected to an input of gates (L L (L L "(L L3) to (L,,,, L,,,'),respectively, to a second input of which gates L the [volume] voltage Uand to a second input of which gates L the voltage U is also applied.The output of gates L and L, respectively, supplies the voltages U and Urespectively, to a row of the pickup elements dependent upon the voltagesupplied by the associated shift register stage K.

The voltage supplied by the m-divider has a recurrence period which isequal to [ram] mxn periods of the voltages U U and U and serves as astarting voltage for the first register stage K This latter thensupplies a voltage to the gates L and L during n-periods as a result ofwhich the voltages U and U; are transferred to the pickup elements B toB The image signal supplied by the first row of pickup elements B to Bappears at the output terminal Z during the n-periods. After then-periods the voltage supplied by the shift register stage K, varies, sothat the gates L and L are closed and the shift register stage K ispulsed so that as a result of the varied voltage supplied by the stage Kthe gates L and L, open for the second number of nperiods. After the innumber of n-periods, the row of the pickup elements B to B has suppliedits image signal to the output terminal Z.

In the description with reference to FIGS. 1 and 2 the time interval Mis shown which occurs between two successive reading out operations of arow of pickup elements B to B For the device shown in FIG. 3, having mrows of pickup elements, the time interval M in a cyclic operationappears to be equal to (m--l) times the reading out interval of a row ofpickup elements. For a television system having 25 images per secondbuilt up to 625 lines, the time interval At is approximately equal to 40ms minus 64 us.

It is obvious that in a simple manner the known interlacing with twoframes can be reached by applying the voltage supplied by shift registerstages K, to the gates L and L while the gates I and L, are connected toa shift register stage which opens the same after approximately/z[m.n.]m n periods.

It is obvious that for deriving a video signal having the so-called lineblanking from the image signal occurring at the output terminal Z, botha part of the information supplied by the rows of pickup elements may beleft unused and the shift register may be adapted by incorporating inthe stages K, for example, a delay which corresponds to the lineblanking time or, for example, the frame blanking time.

The three-fold or two-fold construction of the device shown in FIG. 3results in a camera suitable for color television by dividing the lightcoming from the scene in three or two basic colors.

A semiconductor device constructed as a pickup array in which the pickupelements are preferably integrated in one semiconductor body will now bedescribed with reference to FIG. 4. FIG. 4a diagrammatically shows apart of a plan view of an embodiment of such a semiconductor device,while FIG. 4b diagrammatically shows a cross-sectional view taken on theline IVbIVb in FIG. 4a.

The embodiment shown in FIG. 4 comprises a substrate 40 which may be,for example, of an insulating material, the substrate being providedwith one or more surface regions of a semiconductor material or, as inthe present example, consisting itself of a semiconductor material, forexample, P-type silicon. In a manner commonly used in semiconductortechnology, for example, by means of a conventional photoresist anddiffusion method, surface regions 41 of the opposite conductivity type,for example, having proportions of 64 um. x 64 pm, are provided in asurface region of the substrate 40. These surface regions 41. togetherwith the intermediate regions 42 constitute the semiconductor regions ofa number of MOS transistors. These MOS transistors are arranged inseries, in which each of the regions 41 shown constitutes the output ordrain electrode of a MOS transistor of a series and also the input orsource electrode of the succeeding MOS transistor of that series. Theintermediate regions 42, width, for example, approximately 6 nn 10regions between the source and drain electrode of each MOS transistor.The MOS transistors are furthermore provided with gate electrodes 47,proportions approximately 60 m. it 60 m., which are insulated from thesemiconductor surface by an insulating layer 43', for example, by alayer of silicon oxide, thickness 0.1 m. The gate electrodes 47 arealternately connected to one of the conductive tracks 43 and 44 and 45and 46, respectively. The thickness of the insulating layer below theconductive tracks 43 to 46 preferably is larger than below the gateelectrodes 47 (for example, approximately 0.5 m.) to prevent undesiredchannel formation. Channel interruptors, for example, diffused channelinterruptors, may alternatively be used.

The gate electrodes 47 and the metal tracks 43 to 46 consist, forexample, of gold, and have a thickness of approximately 250 A. Such goldelectrodes are trans parent so that radiation incident on the surfacecan be absorbed in the semiconductor body and the photosensitivity ofthe PN-junctions between the surface regions 41 and the surroundingsurface region of the substrate 40 may be used. In connection herewiththe distance between the surface of the semiconductor body and the saidPN-junctions preferably is approximately 1 m. In the operatingcondition, the said PN-junctions are biased in the [forward] reversedirection to establish a depletion layer around each junction. For thatpurpose the surrounding surface region is connected to a negativepotential, in this case via a connection conductor which is connected tothe substrate 40 and is not shown.

The pickup elements of the pickup array are each constituted by twosucceeding transistors. The two capacitances C C between which atransport of charge may occur dependent upon the information of thephysical pattern, are provided between the gate electrode and the drainelectrode of the two MOS transistors of the pickup element as depictedin F1 1. In the present example, said capacitances are constituted bythe initial capacitance between the gate electrode and the drainelectrode for each MOS transistor, said internal capacitance beingincreased in that the gate electrodes 47 extend for a considerable partof their surface above the surface regions 41. The photosensors whichmodify the stored charge in relation to the incident radiation are, asin the Weckler publication, the photodiodes constituted by thereverse-biased n-p junctions formed between each of the N regions 41 andthe P substrate 40. In the FIG. 3 embodiment, for instance, in thevarious rows of pick up elements, the capacitors which are shownconnected between gate and drain correspond to the capacilances formedacross the insulating layer 43'. The photodiodes would correspond tocapacitors connected between each drain and the substrate. Forcompleteness sake, these are shown in dashed lines only for the firstrow. It will be evident to those skill d in the art that the twocapacitors connected to a comon drain are essentially in parallel andthus mutually influence their charge conditions. The said transport ofcharge can be controlled with control signals which can be applied tothe gate electrode 47 of the MOS transistors through the conductivetracks 43 to 46.

What is claimed is:

[1. A device for converting an energy pattern into an electrical signalas a function of time, comprising a plurality of serially connectedpickup elements; each of said elements comprising an input terminal, anoutput terminal, at least two semiconductor switches each having input,output and control terminals, a capacitor connected in parallel with thecontrol and input terminals of each of the semiconductor switches ineach pickup element, an energy-sensitive conduction path means connectedin parallel with each capacitor for discharging each capacitor at a ratedetermined by the amount of energy incident thereon, means forconnecting the output constitute the channel terminal of a first of thesemiconductor switches in each element to an input terminal of a secondsemiconductor switch in each element, means for connecting the inputterminal of the first semiconductor switch in each element to the inputterminal of that element, means for connecting the output terminal ofthe second semicon ductor switch of each element to the output terminalof that element; the device further comprising an external semiconductorswitch having input, output and control terminals; means for connectingthe output terminal of the external semiconductor switch to the inputterminal of a pickup element on an end of the plurality of seriallyconnected pickup elements, an external capacitor connected to the inputterminal of the external semiconductor switch, means for providing afirst alternating switching voltage to the control terminal of each ofthe first semiconductor switches in each element, means for providing asecond alternating switching voltage to the control terminal of theexternal semiconductor switch and to the control terminals of eachsecond semiconductor switch in each element, and means for providing athird alternating voltage in phase with said second alternatingswitching voltage for charging said external capacitor] [2. A device asclaimed in claim 1, wherein each of the semiconductor switches in eachpickup unit comprises a metal oxide transistor, wherein each of thecapacitors in the pickup units each comprise a PN-junction of anassociated MOS transistor, and wherein the radiation sensitiveconduction path means comprises a photosensitive boundary layer of theMOS transistor] [3. A device as claimed in claim 1, further comprisingan additional row of serially connected pickup elements, an additionalexternal semiconductor switch connected to one end of said additionalrow of pickup units, means for connecting the semiconductor switch tothe external capacitor, and means for alternately energizing said firstand said second external semiconductor switches] [4. A device as claimedin claim 1, wherein all of the semiconductor switches are integratedinto a single integrated semiconductor body] 5. A solid statephotosensitive imaging array comprisa plurality of rows having aplurality of transistors, each transistor having first and secondelectrodes defining the ends of a conduction path and a controlelectrode; the conduction paths of the transistors of a row beingconnected in series for forming a signal transmission path terminated atone end at an output terminal;

a capacitor per transistor coupled between the control electrode and oneof said first and second electrodes of each transistor;

photoresponsive element per transistor, each element being common to thecapacitor at said one electrode of its associated transistor, saidelement being poled in a direction to discharge said capacitor as afunction of photo signals;

two conductors per row, one conductor being connected to the controlelectrode of every other transistor and the other conductor beingconnected to the control electrode of the remaining transistors;

a source of clock voltages;

switch means connected between said conductors of each row and saidclock source for, when enabled, applying between said conductors clockvoltages for serially reading out the contents of a row and concurentlyrecharging the capacitors of a row; and

scan means having an output terminal connected to different one of saidswitch means for enabling said switch means in sequence for completelyreading out and recharging one row and then another one and so on untilall rows are read out.

6. The combination as claimed in claim 5, wherein the scan meanscomprises a shift register having one output per stage, and meansconnecting the output of each stage of the shift register to the switchof a difierent row of transistors.

7. The combination as claimed in claim 6, and further including meansfor coupling said clock source to the shift register of the scan means.

8. Imaging semiconductor apparatus comprising:

a semiconductive wafer including a bulk portion of a first typesemiconductivity and a plurality of spaced, localized zones of oppositetype semiconductivity disposed adjacent and forming a series path alongthe surface of the wafer;

a dielectric layer disposed said localized zones;

a plurality of localized conductive electrodes disposed over thedielectric layer and registered with said localized zones such that eachof said conductive electrodes extends over the space between a pair ofsaid zones and over a portion of one zone of the pair of zones and formswith the latter charge storage means;

means for applying alternating clock voltages between successive ones ofsaid electrodes, said clock voltages being sufficient to produce in thelocalized zones in the absence of incident photons a reference potentialand said clock voltages additionally being such that their successiveapplication to the electrodes is suflicient to cause the advance of anycharge if present representing a variation of the reference potentialfrom one zone to the next zone along the series path at each alternationof the voltages;

means for enabling incident photons to impinge upon the semiconductivewafer to cause in response to the photon intensity adjacent the chargestorage means localized variations from the reference potential, saidlocalized variations representing signal information corresponding tothe local photon intensity; and

detection means for the potential variations coupled to the localizedzone at the end of the said series path, whereby upon application of theclock voltages the signal information can be derived from the saiddetection means in serial fashion.

9. Imaging semiconductor apparatus as set forth in claim 8 wherein thecharge storage means are arranged in a row with a single detection meansfor the row connected to the end of the row, said row being adapted toimage and convert to electrical signals a line of incident photons.

10,. Imaging semiconductor apparatus as set forth in claim 9 whereinplural rows of charge storage means are provided each with a singledetection means at the end of each row.

11. Imaging semiconductor apparatus as set forth in claim 8 andincluding means for applying the clock voltages over a relatively smalltime interval compared with the time interval during which photonsimpinge upon the wafer.

12. A charge transfer imaging device comprising:

a charge storage medium;

an insulating layer covering over said surface and over the chargestorage media plurality of electrode field plates disposed on theinsulating layer and overlying spaced sites within the charge storagemedium wherein charge can be stored when appropriate electrical bias isapplied to the field plates, said charge storage sites forming a seriespath along the medium, said electrode field plates being spaced alongthe insulating layer with each contiguous to at least two other fieldplates such that with appropriate electrical bias applied to saidelectrode field plates electrical charge can be made to passcontrollably through the medium between selected charge storage sitesand ultimately to an output located at the end of the series path andcapable of converting charge to an electrical signal;

13 photo-sensitive means each associated with one of the charge storagesites and capable in response to incident photons to cause a variationin charge stored at the associated site;

means for enabling incident photons to impinge upon the photosensitivemeans; and

means for applying cyclically varying voltages to the electrode fieldplates, said voltages being such as to establish at one set ofnon-contiguous storage sites the appropriate bias for storing charge andto establish in another set of difierent storage sites the appropriatebias for transferring charge therein to said one set and uponsubsequently varying the bias for transferring charge from said one setto said other set and thus along the series path of storage sites to theoutput, whereby from the output can be derived a serial electricalsignal representative of the photonvaried charge condition of theplurality of charge storage sites along the series path.

13. A charge transfer imaging device as set forth in claim 12 whereinthe plurality of charge storage sites form an array of m rows of ncharge storage sites per row, each row being formed by a series path andbeing terminated by a single output, means coupled to the output of eachrow for deriving a serial electrical signal representative of a line ofincident photons, and means for operating the device to provide inserial fashion the electrical signals derived from the m rows to providea video signal of the photon intensity of an image incident on thearray.

14. A charge transfer imaging device body having a semiconductor surfacelayer, layer over the semiconductor surface layer, linearly-arrangedelectrode comprising a an insulating a plurality of field platesdisposed over the insulating layer, said electrode field plates beingdivided into at least first and second sets of non-contiguous plates,source of cyclically varying voltages, means for applying the cyclicallyvarying voltages to the first and second sets such that the plate setsvary in voltage between first and second values which when applied to aplate are copable of establishing in an underlying portion of thesemiconductor layer a site whereat electrical charge can be stored, saidcharge storage sites formed under the first and second plate sets beinglinearly arranged, said charge storage sites comprising a depletionlayer and having a reference potential in the absence of incidentphotons, means for imaging a line of an object onto the device wherebythe photons incident thereon cause a variation representative of thephoton intensity from the reference value in the potential at chargestorage sites along a line, and output means coupled to a storage siteat the end of the line and capable of converting a variation inpotential into an electrical signal, the voltage applied to one set offield plates being different than that applied to the other set of fieldplates whereby during the first voltage value charge representative of apotential variation is caused to flow through the semiconductor layertoward the output between storage sites located under the first plateset toward storage sites located under the second plate set and duringthe second voltage value charge representative of a potential variationis caused to flow through the semiconductor layer toward the the outputbetween storage sites located under the second plate set toward storagesites located under the first plate set and so on, whereby localizedpotential variations at storage sites are transferred along the line andthus from the output can be derived an electrical signal representativeof photon-varied charge conditions.

15. A charge transfer imaging device as claimed in claim 14 and furthercomprising plural lines of linearlyarranged electrode field platesdefining plural lines of charge storage sites to form a two-dimensionalarray of lines.

16. A charge transfer imaging device as claimed in claim 15, wherein acommon output means is coupled to the two-dimensional array of lines.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original State ImageSensors" by Weckler, May 1967, pp. -79. JERRY D. CRAIG, Primary ExaminerUS. Cl. X.R. 307-221 D, 304; 178-11; 317-235 G, 235 N Dated M h 25 1&14

Patent NO-Rp 2'1951 Inventor(s) i It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

.Column 4, line 72, change "which" to while Column 10, line 39, change"initial" to internal Signed and sealed this 27th day of August 1974.

(SEAL) Attest:

MCCOY M. GIBSON, "JR.

Atte-sting Officer C. MARSHALL DANN Commissioner of Patents

